The present invention relates to a catadiotropic device or retro-reflector, i.e. an optical device which reflects back any incident light ray comprised in a given operating field, along its incidence direction.
Such devices are used in various fields, particularly for obtaining an optical telemeter or an optical responder.
U.S. Pat. No. 4,097,125 and British Pat. No. 1,401,687 disclose image formation devices with unity magnification and incorporating a concave spherical mirror forming the main mirror and a convex spherical mirror forming a secondary mirror which faces the main mirror and is coaxial therewith. The radius of the second mirror is smaller than that of the main mirror and can in fact be half that of the latter. The centres of curvature can be slightly displaced in accordance with the common optical axis of the device by moving the secondary mirror towards the main mirror to correct the spherical aberration.